At issue is at least one of the NSA programs disclosed by the Guardian last week: the government's use of a provision of the Patriot Act to collect the call data of most Americans' phone calls to create a master database of all calls made in the US for the last five years. According to Senate intelligence committee chair Dianne Feinstein and others, the government uses the database to check whether Americans have called numbers associated with suspected terrorists.

In a hearing before the House judiciary committee, a number of representatives – including John Conyers, Jim Sensenbrenner, Jerry Nadler, Bobby Scott, Sheila Jackson-Lee, and Jason Chaffetz – asked the director to justify obtaining data on all Americans. Sensenbrenner pointed out, for example, that the FBI could use a grand jury subpoena or a "national security letter" to obtain the same information directly from a phone company.

And while Mueller did claim that the dragnet program would have prevented 9/11 (ignoring that the FBI had authority to get the information in question at the time, and that a number of other bureaucratic failures may have contributed to the intelligence community's failure to prevent the attack, too), his favorite justification for gathering all the metadata from all US phone calls amounts to "because we can".

The US supreme court has held that phone metadata is not protected by the fourth amendment, Mueller said repeatedly. He was referring to a 1979 supreme court case, Smith v Maryland, which held that people did not have a reasonable expectation of privacy regarding the numbers they call, because they willingly give up those numbers to the company to connect their call.

And so, because the supreme court approved the collection of one robber's phone records in 1979, Mueller insisted, it meant it was reasonable for FBI and NSA to collect and aggregate the phone records for every American today and for ever.

Mueller even used the same reasoning to address a question from Californian congresswoman Zoe Lofgren about whether it was appropriate for Department of Justice to subpoena the call records of a phone in the congressional press office during the AP leak investigation. Lofgren was upset that those records would have revealed conversations between the press and members of Congress – an infringement of the first amendment, but also of Congress's protection under the constitution's "speech and debate" clause.

Because it was just metadata, Mueller proposed, collecting that data didn't cross the line of appropriateness.

New York Representative Jerry Nadler wasn't convinced Mueller's excuse was good enough. He noted that metadata includes so much more information than it did in 1979, and that that earlier ruling might not stand in this case. Utah's Jason Chaffetz got much more specific about the difference between phones in 1979 and now: location.

Landlines include location information. But with cell phones, the same location information necessary to route a call effectively provides a rough idea of where a person is even as they move from place to place (map functions on smart phones, as well as a lot of applications, rely on this data). Thus, the geolocation available as part of cell phone metadata provides a much better idea of where a person goes and what they do than location data for a landline tied to a person's address.

Chaffetz posed several questions that, he revealed, he had sent Mueller Wednesday so that he would be prepared to answer, starting with whether or not geolocation is part of this metadata collection. In spite of Chaffetz's prior warning, Mueller said he did not know whether it was included.

Note that the order to Verizon the Guardian publishedspecifically includes routing information in its description of metadata, which gets to geolocation. It's clear this collection includes geolocation.

Mueller was also unprepared to answer whether or not a different supreme court case from last year, US v Jones, which determined that installing a GPS tracking device on a suspect's car constituted a search, meant that the geolocation provided by the GPS function on cell phones did not qualify as metadata. Mueller was also unprepared to answer whether tracking someone's location by using their phone constituted metadata.

In fact, Mueller admitted his staffers had told him he'd be asked these questions – yet still hadn't prepared. It seemed almost as if his inability to answer this question in public was intentional.

But perhaps Mueller's most telling response about metadata came in response to questions posed by Hank Johnson, a Democrat from Georgia. He raised the other program exposed by the Guardian, the government's ability to access internet company's data directly, and described Google's request to publish the number of times the government uses such access in aggregate form, as the company does with other data requests.

That data – searches in aggregate, rather than specific descriptions of each search – is a form of metadata, Johnson quipped. Unsurprisingly, Mueller seemed reluctant to share when it came to his agency's own metadata. It seems he worries that terrorists – or even privacy-loving consumers – might pick internet service based on how frequently they let the government access their data directly.

Funny: Mueller seems to understand that metadata can be tremendously revealing – when it comes to his wish to avoid scrutiny.